The present invention relates to a method of determining the concentration of spherical solids used as lubricants in a drilling fluid.
U.S. Pat. No. 4,063,603 to Rayborn discloses a method of borehole drilling in which the drilling fluid or mud contains spherical plastic beads which are used to reduce friction between the drill string and the well bore and thereby reduce the amount of torque required to rotate the drill string during the drilling process. As is pointed out in the cited patent, in certain cases, the addition of the plastic beads beyond a certain amount does not materially reduce the torque required to rotate the drill string. Accordingly, a method of determining the concentration of the plastic beads in the drilling mud is desirable to ensure that the optimum amount of such beads is used.